Cassidy, born of the Irish surname Ó Caiside—‘descendant of Caiside,’ a by-name traditionally glossed as “curly-haired” and, by some lexical sleight of hand, “clever”—travels across the Atlantic like a swift syllabic swallow, alighting in American playgrounds with the gently lilting pronunciation KAS-i-dee. In the wake of 1970s pop-culture luminaries David and Shaun Cassidy, the appellation shed its purely patronymic cloak and, with a touch of irony worthy of Horace’s ars poetica, settled most comfortably upon baby girls: it vaulted from a scarcely noted rank in the late 1960s to a dazzling No. 99 by 1999, and though it now sails in the mid-400s, it remains a sturdy craft in the onomastic fleet. The name’s dual mystique—equal parts emerald-isle romance and frontier swagger, thanks to the folkloric shadow of Butch Cassidy—gives it a resilient vitality: one can almost hear a fiddle’s jig blending with a mariachi trumpet as the child called Cassidy toddles onto the global stage, a small ambassador of Celtic cadence warmed by Latin sunlight.
| Cassidy Jacqueline Hutchinson is a former White House aide and assistant to Chief of Staff Mark Meadows in the first Trump administration. | 
| Cassidy Janson is a British musical theatre actress who won the 2020 Olivier Award for Best Supporting Performance in a Musical for and Juliet. | 
| Cassidy Freeman is an American actress and musician best known for playing Tess Mercer on Smallville, Cady Longmire on Longmire, Amber Gemstone on The Righteous Gemstones, and Sage on The Vampire Diaries. | 
| Cassidy Erin Gifford is an American actress known for co-starring in the 2017 film Like Cats and Dogs and for playing Reagan Decker in the Prime Video series The Baxters. | 
| Cassidy Rae Joyce is a retired American actress. |